The present disclosure relates to a vibratory actuator in which a plurality of piezoelectric layers are stacked.
Conventionally, a vibratory actuator has been known, which includes piezoelectric elements (electromechanical transducer elements), and which is used for various electric devices. Such a vibratory actuator includes a plurality of stacked piezoelectric layers; and internal electrodes, each of which is sandwiched between the piezoelectric layers. In the vibratory actuator, voltage is applied to the piezoelectric layers through the internal electrodes to induce desired vibration in the piezoelectric layers, resulting in an output of drive force.
In, e.g., a vibratory actuator of Japanese Patent No. 4069160, a plurality of piezoelectric layers including internal electrodes formed on principal surfaces thereof are stacked, i.e., the piezoelectric layers and the internal electrodes are alternately stacked. Thus, each of the internal electrodes is sandwiched between two piezoelectric layers. The internal electrode extends to a side surface of the piezoelectric layer. A side electrode is formed on the side surface of the piezoelectric layer, and the internal electrode is connected to the side electrode. When the plurality of piezoelectric layers are stacked, the side electrodes of the piezoelectric layers are connected in the stacking direction to function as a single side electrode. External electrodes through which power is fed from outside are formed on the principal surface of the outermost piezoelectric layer, which is exposed to outside (surface facing the stacking direction). The external electrode extends to and is connected to the side electrode positioned on the side surface of the piezoelectric layer. That is, the external electrode is in conduction with the internal electrodes through the side electrode. A wire is connected to the external electrode. In the vibratory actuator configured as described above, voltage is applied from outside to the vibratory actuator through the wires, thereby applying such voltage to the internal electrodes through the external and side electrodes.